Turbine apparatus



Aprifl 16, 1. A. EGLI 2,197,521

TURBINE APPARATUS Filed April 21, 1938 Ha im ll/llllll/l/lIII/IIj Fm a.

ll WITNESSES: INVENTOR HDOLF' Equ. BY J v 'BIM ATTORNEY Patented Apr.16, 1940 UNITED STATES PATENT OFFICE Application April 21, 1938, SerialNo. 203,254

2 Claims.

My invention relates to steam turbines and more particularly to stagesthereof of the partial peripheral admission impulse type and it has foran object to provide for gradual acceleration of steam in blade passagesas the latter enter the nozzle region.

In a partial peripheral admission impulse stage, the steam remainspractically at rest in the rotating blade passages as long as the latterare not in the nozzle zone. Accordingly, as a blade passage enters thenozzle zone, the steam therein must be accelerated by the initial jet orjets before normal flow through the blade passage is established.Acceleration of the fluid involves pressures and velocities whichproduce axial forces on the blades larger than those of the steady stateflow. In some cases, such an axial force acting on the blades may beexcessive, and it is the object of the present invention to reduce thevelocity in the initial nozzle or nozzles of a group in order to reducethe rate of acceleration and therefore the axial force acting on theblades.

A more particular object of my invention is to provide the initialnozzle or nozzles of a group with orifices serving to throttle theadmission to the initial nozzle passage or passages for the purpose ofreducing the velocity in such passage or passages relatively to thevelocity in the remaining passages.

These and other objects are effected by my invention as will be apparentfrom the following description and claims taken in connection with theaccompanying drawing forming a part of this application, in which:

Fig. 1 is a sectional view of a two-row impulse turbine stage having myimproved nozzle group; and,

Fig. 2 is a detail developed sectional view showing my improved nozzlegroup.

In the drawing, there is shown a rotor l0 and a stator ll carrying,respectively, the rotating blades l2 and I3 and the interveningstationary blades M, the rotating rows of blades I2 and I3 and theintervening stationary row of blades l4 constituting the usual two-rowimpulse stage.

Steam at suitably high velocity is supplied to the initial row of blades[2 by means of a nozzle group, at E5, communicating with a nozzlechamber l6.

As the rotating blades are not subject to the influence of steam issuingfrom the nozzle passages for a considerable portion of each revolution,it will be apparent that steam remains at rest relative to the movingblade passages as long as the latter are not in the nozzle zone.Therefore, referring to Fig. 2, with the blades l2 moving in thedirection of the arrow,it will be apparent that just as soon as a bladepassage is acted upon by the jet or steam issuing from the initialnozzlepassage ll, steam in the blade passage will be accelerated by the jetand axial as well as lateral force will be applied to the bladesdepending upon the rate of acceleration.

The rate of acceleration, and consequently the 10 magnitude of the axialor lateral force, is reduced by throttling the admission of steam to theinitial passage, such passage having a box or cover 20 separating theentrance thereof from the nozzle chamber l6 except for the orifice ornozzle 2|. The orifice or nozzle 2| restricts the flow of steam from thechamber IE to the nozzle passage, that is, it establishes a pressuredrop in series with the pressure drop in the nozzle passage ll, thelatter pressure drop determining the 20 jet velocity. By this means, thejet velocity of the passage I1 is reduced over what it would be withoutthe cover 26) and the orifice or nozzle 2!; and, in consequence, thesteam in the blade passage is accelerated less rapidly as it comes 5under the influence of the jet and the magnitude of the lateral forceinduced on the moving blades corresponding to the acceleration is alsoreduced. 9

A more gradual acceleration effect may be had by progressivelyincreasing jet velocities. Accordingly, in Fig. 2, the initial nozzlepassage ll has the adjacent passage I8 supplied with steam by a largerorifice or nozzle 22. The remaining nozzle passage or passages l9 of thegroup are in direct communication with the nozzle chamber [6.

While I have shown my invention in but one form, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof various changes and modifications without departing from the spiritthereof, and I desire, therefore, that only such limitations shall beplaced thereupon as are imposed by theprior art or as are specificallyset forth in the appended 5 claims.

What I claim is:

1. In a steam turbine, a row of moving blades, means defining a nozzlechamber, means providing for the partial peripheral admission of 50steam to the row of moving blades from the nozzle chamber and comprisinga plurality of nozzle passages, and a cover for the initial nozzlepassage of the group considered in the direction of motion of the movingblades and separating the inlet of said passage from the nozzle chamher,said cover'having an orifice for supplying steam from the nozzle chamberto the initial nozzle passage.

2. In a steam turbine, a row of moving blades, means defining a nozzlechamber, means providing for the partial peripheral admission of steamto the row of moving blades from the nozzle chamber and comprising aplurality of nozzle passages, and a cover for a plurality of nozzlepassages at the end of the group approached by the moving blades, saidcover having orifices for admitting steam from the nozzle chamber to therespective passages and said orifices increasing in size in thedirection of blade travel in order to provide for gradual increase invelocity of the jets.

ADOLF EGLI.

